title: Protection against pathogen and salt stress by four plant growth-promoting rhizobacteria isolated from Pinus sp. on Arabidopsis thaliana.
abstract: The ability of four plant growth-promoting rhizobacteria, isolated in a previous study, to induce systemic resistance on Arabidopsis thaliana Col 0 against biotic and abiotic stress was evaluated. All the bacteria enhanced protection against the foliar pathogen Pseudomonas syringae DC3000 and increased plant tolerance to salt stress (NaCl 60 mM). Bacillus sp. strain L81 and Arthrobacter oxidans strain BB1 performed best with a decrease in the disease index of 61.2 and 52.3%, respectively, and a reduction in the mortality due to salt stress of 72.4 and 57.8%, respectively. Additionally, significant differences were found in growth and photosynthesis, again, L81 and BB1 performed best either in normal or under stress conditions. In order to elucidate the pathway elicited by these two strains to induce systemic resistance, experiments with the transgenic line of Arabidopsis thaliana NahG (defective in salicylic acid [SA]) and with the jar1 mutant (defective in jasmonic acid) were carried out. Results showed that the SA-dependent pathway was involved in the defense response induced by strains L81 and BB1. Results from quantitative reverse transcription-polymerase chain reaction analysis of the PR1 gene, related to the SA-dependent pathway and the PDF1.2 gene related to the SA-independent pathway, showed an increased expression of PR1 in BB1-treated plants, confirming involvement of the SA-dependent pathway in the defensive response.
authors.affiliation: Universidad San Pablo CEU, Facultad de Farmacia, Boadilla del Monte, Madrid, Spain. jbarriuso@ceu.es
authors.forename: J
authors.initials: J
authors.lastname: Barriuso
authors.forename: B Ramos
authors.initials: BR
authors.lastname: Solano
authors.forename: F J
authors.initials: FJ
authors.lastname: Gutiérrez Mañero
mesh_terms: D000898:Antibiosis; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000382:microbiology*; D001173:Arthrobacter / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D001407:Bacillus / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology; D003517:Cyclopentanes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate; D054883:Oxylipins / Q000378:metabolism; D028223:Pinus / Q000382:microbiology*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology; D044224:Pseudomonas syringae / Q000254:growth & development*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020156:Salicylic Acid / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D010940:Plant Proteins; D012965:Sodium Chloride; C011006:jasmonic acid; D020156:Salicylic Acid